/// <summary>
/// Projects a PointF along a specified direction
/// </summary>
public static PointF ProjectAlong(this PointF This, PointF direction)
{
var normalDirection = direction.Normalize();
var dist = This.DotProduct(normalDirection);
return(normalDirection.ScaledBy(dist));
}
private double CosBetween(PointF a, PointF b)
{
var dotProduct = a.DotProduct(b);
var lenA = a.RadiusVector();
var lenB = b.RadiusVector();
return(dotProduct / (lenA * lenB));
}
/// <summary>
///
/// </summary>
/// <param name="other"></param>
/// <returns>paramter of intersection equation. NaN if no intersection</returns>
public double Intersect(Edge other)
{
var t = Double.NaN;
PointF a = Origin;
PointF b = Destination;
PointF c = other.Origin;
PointF d = other.Destination;
PointF n = new PointF(d.Substract(c).Y, c.Substract(d).X);
var denom = n.DotProduct(b.Substract(a));
if (denom != .0)
{
var num = n.DotProduct(a.Substract(c));
t = -num / denom;
}
return(t);
}
public void PointExtensions()
{
var x1 = 1;
var x2 = 2;
var y1 = 3;
var y2 = 4;
var p1 = new PointF(x1, y1);
var p2 = new PointF(x2, y2);
var zero = new PointF(0, 0);
var sum12 = p1.Add(p2);
AreEqual(new PointF(x1 + x2, y1 + y2), sum12, "Addition");
AreEqual(p1, sum12.Subtract(p2), "Subtraction");
AreEqual(p1.Add(p1), p1.Multiply(2), "Multiply by 2");
Assert.AreEqual(x1 * x1 + y1 * y1, p1.LengthSquared(), 1e-5, "Length");
Assert.IsTrue(p1.LengthSquared() > 0, "non-zero length");
var normed = p1.Normalize();
Assert.AreEqual(1, normed.LengthSquared(), 1e-5, "length after normalization");
Assert.Throws <ArgumentException>(() => zero.Normalize(), "Can't normalize a zero length vector");
Assert.AreEqual(p1.LengthSquared(), p1.DotProduct(p1), "Length and dot product with itself should match");
}
public static PointF ProjectAlong(this PointF This, PointF direction)
{
PointF @this = direction.Normalize();
return(@this.ScaledBy(This.DotProduct(@this)));
}